Invalidity dossier
US 6542090
Character input apparatus and method, and a recording medium
Current assignee: Microsoft Technology Licensing LLC
Added 8/26/2026, 11:04:47 PM
Active provider: DeepSeek · deepseek-v4-flash
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Patent summary
Title, assignee, inventors, filing/issue dates, abstract, and a plain-language overview of the claims.
I'll search for the specific patent number 6542090 in the USPTO database and check for any CAFC 2026 docket activity.
I have confirmation of the patent's core details. Now let me check for any CAFC 2026 docket activity involving this patent number.
No CAFC 2026 results found. Let me do one more check on USPTO records and any post-grant proceedings.
US Patent 6,542,090 (US6542090B1) — Summary
Note on scope: I searched for the literal identifier 6542090 only. No results for any similar numbers were included.
Bibliographic data
| Field | Value |
|---|---|
| Title | Character input apparatus and method, and a recording medium |
| Patent No. | US 6,542,090 B1 (application no. 09/417,970) |
| Filing date | October 13, 1999 |
| Issue date | April 1, 2003 |
| Priority date | October 14, 1998 (Japanese application JP 29258398 / published as JP2000122768A) |
| Inventors | Masayoshi Tadano, Osamu Adachi, Takeshi Fujimura (listed on Google Patents as "Fujimura Takeshi"), Toshiaki Kikka |
| Original assignee | Microsoft Corporation (assignment recorded Feb. 11, 2000); reassigned to Microsoft Technology Licensing, LLC on December 9, 2014 |
| Current status | Expired – Lifetime (anticipated expiration date: October 13, 2019, i.e., 20 years from filing) |
| Cited reference | US 6,073,146 A (IBM – Chinese language text processing), cited by the examiner |
Abstract
"A character input apparatus and method which can give a plurality of different character input mean a capability of complementing each other."
In plain terms: the invention lets a user enter Japanese (or other) text by mixing input methods — keyboard (kana/romanized), handwriting (via mouse/pen), and speech recognition — into a single unfinalized character buffer, in the order entered. The mixed string can then be finalized as a block using conventional character processing (e.g., kana-to-kanji conversion, character-kind conversion, insert/delete), instead of requiring each input device's characters to be finalized separately before being combined. This lets one input method substitute for another (e.g., handwriting can supply a key that is broken).
Independent claims (plain-language overview)
There are 18 claims, with three independent claims (1, 7, 13) — an apparatus claim, a method claim, and a recording-medium/program claim:
- Claim 1 (apparatus): A character input apparatus having (a) multiple character input means using different input methods; (b) memory means that store the entered characters in the order entered, regardless of which input means produced them; and (c) character processing means that process the stored string to finalize the input character string. The key concept is that characters from all input means are pooled as unfinalized characters that can be finalized together.
- Claim 7 (method): The corresponding method — inputting characters by different methods; storing them in a memory device in the order entered; and processing the stored character string to finalize it.
- Claim 13 (recording medium): A computer-readable recording medium storing a program that, when executed in a character input apparatus, performs the same input → ordered storage → finalization-processing steps as claim 7.
Dependent claims (overview)
Claims 2/8/14 add a character-processing range specifying means/step (user can select a sub-range of the stored string to process). Claims 3/9/15 add display means/step showing unfinalized vs. finalized strings in different display forms (e.g., different colors or underlining). Claims 4/10/16 specify the processing includes kana-to-kanji conversion of the unfinalized string. Claims 5/11/17 specify insertion or deletion of characters. Claims 6/12/18 specify character-kind conversion (e.g., hiragana/katakana/alphanumeric).
CAFC 2026 docket search
I searched for "6542090" and "6,542,090" in connection with CAFC/Federal Circuit 2026 dockets, appeals, and litigation. The searches returned no results, so I found no evidence of any CAFC 2026 appeal or other Federal Circuit activity involving this patent. Given the patent expired in 2019, any 2026 appellate litigation would be unlikely, but I cannot rule it out from my searches — treat the absence of CAFC activity as "not found," not "confirmed absent."
Uncertainty / data-quality flags
- The Japanese text (kana/kanji) is stripped from the Google Patents/Justia HTML copies; the specification's examples (e.g., "東京駅") render as empty strings. The substantive meaning is unaffected.
- Google Patents lists a "Related Child Application" (US09/916,649 → US6585666B2) titled "Arthroscopic diagnostic probe to measure mechanical properties of articular cartilage." This appears to be a data error on Google Patents — an unrelated medical-device patent mislinked to this character-input patent. I did not verify this via USPTO and flag it as likely erroneous.
- Maintenance fees were paid at the 4-, 8-, and 12-year marks (2006, 2010, 2014), so the expiration was by term (20 years), not by fee nonpayment.
Generated 8/26/2026, 11:05:12 PM
Cases on file (0)
Specific litigation cases in our database that name US patent 6542090. The free-form analysis below may also discuss cases beyond this list.
No cases on file mention this patent. Upload a CSV or add a case manually in Admin → Manage litigation cases.
Litigation summary
Past and pending lawsuits — plaintiffs, defendants, jurisdictions, outcomes, and notable rulings.
Proceedings on file (0)
All PTAB activity →AIA trial proceedings (IPR / PGR / CBM) filed at the USPTO Patent Trial and Appeal Board against this patent. Sourced from the USPTO Open Data Portal and refreshed every six hours; each proceeding number deep-links to the PTAB E2E docket.
No PTAB proceedings on file. This patent has not been challenged via IPR, PGR, or CBM. The absence is itself a signal — well-asserted patents eventually attract IPRs. The LLM analysis below may surface filings the ODP feed hasn’t indexed yet.
PTAB challenges
AIA trial proceedings at the USPTO Patent Trial and Appeal Board — IPR, PGR, and CBM. Petitioners, judge panels, claim-level invalidation outcomes from Final Written Decisions, and Federal Circuit appeals. The single most important defensive datapoint after litigation history.
Assignment history
Inventors, original assignee, and the chain of ownership recorded with the USPTO — including the correspondent attorney who recorded each assignment, since shell-LLC chains often share one repeat-player attorney even when the entity names look unrelated. Surfaces NPE / patent-troll patterns: shell-entity transfers, known asserters in the chain, repeat correspondent fingerprints, pre-litigation assignments, and bankruptcy fire-sales.
Prior art
Earlier patents, publications, and products that may anticipate or render the claims unpatentable.
Obviousness
Combinations of prior art that suggest the claimed invention would have been obvious under 35 U.S.C. § 103.
Extensions
Patent term adjustments, term extensions, continuations, divisionals, family members, and expiration dates.
Derivative works
Defensive disclosure: derivative variations of each claim designed to render future incremental improvements obvious or non-novel.
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